Processes for the oxidation and conversion of mercaptans contained in a sour petroleum distillate wherein the distillate is treated in admixture with an oxidizing agent in contact with a metal chelate mercaptan oxidation catalyst at oxidation reaction conditions, have become well known and widely practiced in the petroleum refining industry. Said processes are often advantageously effected in a fixed bed treating system wherein the metal chelate mercaptan oxidation catalyst is adsorbed or impregnated on a solid adsorbent support or carrier material disposed as a fixed bed in a treating column. The sour distillate is typically passed in contact with the catalytic composite in admixture with an oxidizing agent and an aqueous caustic solution. The catalytic composite generally requires periodic reactivation, reactivation being effected in situ, for example, by water-washing at an elevated temperature in accordance with the method of U.S. Pat. No. 3,148,156, or water-washing at an elevated temperature followed by a steam treatment in accordance with the method of U.S. Pat. No. 4,009,120, or sequentially washing the catalytic composite with water, dilute acetic acid and alcohol pursuant to the method of U.S. Pat. No. 3,326,816, the washing in some cases being followed by reimpregnation to re-establish a desired concentration of the metal chelate component of the catalytic composite. In time, depending on the character of the sour petroleum distillate being treaated, the catalytic composite will no longer respond to conventional reactivation methods and must be replaced.